Modified lubricating oil



Patented July l, 1941,

MODIFIED LUBRICATIN G OIL Ulric B. Bray, Palos Verdos Estates, andDonald E.

Carr, Los Angeles, Calif., assignors to Union Oil Company of California,Los Angeles, Calii'., a corporation of California No Drawing.Application November 23, 1936, Serial No. 112,352

7 Claims.

This invention relates to lubricating oils and particularly to theimprovement of .very heavily treated or highly refined minerallubricating oils to correct them for apparently undesirable effects suchas corrosion of modern type bearings,

ring-sticking and the like, due apparently to what may be termedovertreatment resulting in the removal of protective agents by"deep-cutting modern solvent treating processes.

More recently the use of various selective solvents' such as liquidsulfur dioxide-benzol mixture. phenol, dichlorethylether and thelikehave been employed for the extraction of both Eastern or paraflinictype, and Western or asphaltic and naphthenic type oils. Theseextractions resulted in the removal of large quantities ofcarbon-forming, naphthenic, unsaturated, and other types of materialsnot strictlyparafiinic in nature which.

have been considered by many investigators to be less desirable inlubricating oils. However, it appears that not only have the undesirablematerials been removed by such treating processes,

"distillate are extracted with liquid sulfur dioxide,

but also protective agents of some type have been removed which preventor counteract the formation of corrosive compounds, ring-stickingcompounds and the like.

stituents can be added to or returned to the final lubricating productand thereby overcome the corrosive, ring-sticking and othercharacteristics above mentioned. l'he preferred fractions of theseextracts are the intermediate or heart out constituents; these may ingeneral be considered as consisting largely of preferred stable aromaticmaterials associated with naphthenic constituents also removed by theaction of the selective solvent. The heavier unstable aromatics,resinous and tarry materials and the like are objectionable and areremoved as by some form of extraction or precipitation and discardedbecause they sludge too readily. The lighter materials preferably arealso eliminated, as by means of some form of solvent extraction, becausethe tend to excessive ring sticking.

This invention therefore resides in the separation from the solventextractsobtained from extracting lubricating oil stocks as abovedescribed, of lighter gravity extract constituents consisting chiefly.of stable aromatic fractions and naphthenes. and employing these insmall percentages in the highly refined lubricating oils produced bysaid solvent treating processes, or

similar very highly paramnic oils exhibiting similar characteristics.More particularly the invention includes the use of intermediate orheart cut fractions of said solvent extracts from petroleum lubricatingstocks, as represented by materials having a gravity in the order of 13to 18 A. P. I. The invention further includes the modified miner-a1 oilproducts or blends so obtained.

As illustrative of this invention, oils such as a deasphalted anddewaxed S. A. E. 50 lubricating and the extract (after driving oil thesulfur dioxide) mixed with propane at atmospheric pressure, under whichconditions a considerable pro,- portion of the extract goes intosolution with the propane. Again, the same type of dewaxed S. A. E. 50lubricating distillate may be extracted with phenol according to knownprocedures to yield anextract having a gravity ofabout 12 A. P. I. atF., the raffinate being highly parafiinic. For purposes of thisextraction about 250 volume-percent of phenol are used at 125 F. and theextract is in turn extracted with8 volumes of propane at to F. Afterdriving oil. the propane, this yields a propane-soluble phase amountingto about 60% of the phenol extract. In this fashion the heavy materialsincluding petroleum resins and tarry bodies in general and unstable andhighly aromatic materials are re- Jected and fighter portions of theextracts are obtained which have good lubricating properties inthemselves. By acid-treating the propanesoluble fraction while stilldissolved in the propane and employing about 25 lbs. of 98% sulfuricacid per barrel of oil at 80F., the propane being present to the extentof about 5 to 8 volumes, and then following with a treatment of 5% clayat somewhat elevated temperature, namely about 350 F., remainingunstable aromatic and kindred materials are removed whereby a valuablenaphthenic and aromatic oil stable in character and of unusually highviscosity and flash point is obtained. Such oil has a viscosity gravityconstant of .888 and an A. P. I. gravity of 16.2, as against the V. G.C. of .903 and an A. P. I. gravity of 13.7 for the propane-solubleportion without acid tr atm n d'as a ainst a ,V. G. C. or .918 and agravity of 11.5 for the phenol extract itself before propane treatment.The temperatures given are merely indicative. For instance, the propaneextraction of thephenol extract may be run at temperatures anywhere fromaround 70 to. 90 F. up to F., this treatment causing the propane toreject the heavy insoluble tar phase while taking a heavy lubricatingmaterial into solution. The temperature for the acid treatriedon-according to any known or preferred procedure.

Similar treatments of liquid sulfur dioxide extract or of extractobtained with mixtures of liquid sulfur dioxide and benzene may be made.These extracts of course vary to some extent, but in each instance theheavy portions will be removed as by precipitation with propane or byacid treatment or both, and the lighter materials may also be removedwhen objectionable. It is always desirable to reject the heaviestportions of the extracts in some manner, of which the propane solutionmethod is a convenient procedure; this readily eliminates the unstablearomatics. Where the light constituents are objectionable because ofbeing present in amount to produce excessive ring sticking or for otherreason, they may be eliminated as by another selective solventextraction which recovers desirable constituents. Again, seriestreatments of lubricating stocks with the solvents mentioned may berelied upon to obtain the desired intermediateor heart cut extract. Herethe first step will be comparatively light and will remove the heavytarry and unstable highly aromatic materials.

The next cut will be deeper and may. recover the desirable intermediatefractions of the present invention." The next cut may then be stilldeeper so as to remove objectionable lighter materials such asnaphthenes. Of course, it is to be understood .that in practice each ofthese three stages of extractions may consist of a plurality of steps.All of these 'heart cut fractions which have been freed from 'both theheavier and lighter constituents are in themselves good lubricating\materials as above indicated, and when blended with heavily refined orvery highly parafiinic lubricating oils, as heretofore mentioned, impartto said oils the desirable characteristics sought by the presentinvention, that is, to overcome corrosiveness, ring sticking and thelike. They also impart oiliness and improved film strength.

The intermediate extracts and in some instances mixed intermediate andlight extracts, such as those having an A. P. I. gravity of about 13 to18 and being free from tarry and resinous materials and unstable highlyaromatic materials, are then added to the above mentioned highly refinedlubricating raffinates in com-- paratively small quantities, in theorder of to of the lubricating oil. This includes the portions of phenolextracts and liquid sulfur dioxide-extracts soluble in propane attemperatures around normal, for example from about 60 or 70 F. to 100 or110 F., and also includes the lightly acid treated propane-solubleportions of said extracts as above described, The acid treatment is.used to eIiminate heavier constituents which may not be desired butwhich, however, were taken into solution in the propane. Not only theextracts obtained from lubricating fractions may be employed butextracts obtained from transformer oils and spray oils by liquid sulfurdioxide treatment, as effected by the well known'Edeleanu process, maybe employed in like manner. Where series treatments are employed, theintermediate extracts will, in

general, be preferred, although the final extracts also sometimes havevalue when not too rich in ring-sticking constituents. Such extracts maybe used without propane treatment or acid treatment. Other solvents thanthe phenol, liquid sulfur dioxide and benzol-sulfur dioxide above.

mentioned, may be employed such as dichlorethyl ether, furfural andothers known for selective extraction, including nitrobenzene andchloraniline.

Any form of extract of the character described is within the scope ofthis invention regardless of the method of obtaining it. For example,the lubricating stock may be exhaustively vacuum distilled to leave aheavy resinous fraction. This heavy residue may then be solventextracted to obtain a out having the desirable stable aromatic materialswithin the range above described. The heavy portions will be discardedand the lightest portions may be either retained or discarded accordingto their ring-sticking and other characteristics, as above described.

It is to be understood that in some instances after the heavier portionsof the extract have been eliminated, the lighter materials may beretained so long as they do not produce ring but will produce excessivering sticking in Diesel engines. For a general purpose .oil, only theheart out or intermediate fraction of the extracts will be returned tothe heavily refined lubricating oils mentioned. By reason of havingeliminated the heavy materials including the unstable highly aromatics,and by reason of having eliminated the lighter extract materials whichtend to ring-sticking or other difficulties, the resultant blend of thehighly refined or highly parafilnic oil and intermediate extractconstituents will produce non-corrosive, non-sticking, non-sludgingparafiinic-type lubricating oil of great desirability for all practicalengine lubricating purposes, and for other purposes as well.

Suitable extract fractions sometimes may be obtained by making a singleselective-solvent extraction, andthen treating the extract with sulfuricacid somewhat as aboveoutlined to remove the heavy, tarry, highlyaromatic and reactive constituents and similar materials and yield astable aromatic-type extract of the present invention.

The highly parafiinlc oils with which these such as Cabin Creek (Penn.)crude will yield'a lubricating Bright stock" of about .801V. G. C. andabout V. I. with 27.5 A. P. I. gravity and about seconds Sayboltviscosity at 210 F. These oilsare not thoroughly satisfactory for suchuses as airplane and Diesel engine lubricants, because they tend tocorrosion of bearings and ring-sticking. It is to such oils as thesethat th herein described extracts are adapted in varying amounts such as5% to 10% or more to overcome such objectionable characteristics. Suchblends will have V. G. C .s of about .811 to .815 according to theamount of extract added to produce the desired modification.

istry, vol. 20, page 641 (1928).

The term viscosity index (V. I.) is defined by Dean and Davis inChemical and Metallurgical Engineering, vol. 36, 1929, page 618. Theviscosity index of a lubricating oil is an indication of its compositionor type, i. e., whether it is a paraffin or naphthene base oil. Paraflinbase oils are arbitrarily assigned a viscosity index of 100, and certainnaphthene base oils from the Gulf Coast are assigned a viscosity indexof and mixed base'oils lie between these-extremes. The termviscosity-gravity constant (V. G. C.) is defined by Hill and Coats inthe Journal of Industrial and Engineering Chem- This constant representsthe parafilnicity or naphthenicity of a given oil. A high valueindicates a high degree of naphthenicity while low values indicaterelatively greater paraflinicity. Lubricating oils from natural crudesrange from .903 (for an extreme Gulf Coast type) to .807 for an extremePennsylvania type, or even beyond.

Somewhat, similar ends may be obtained by regulating the solventextraction in the production of a lubricating oil with solvents.Thecomextract is returned to the oil, anopportunity however beingafforded for removal of the heavy unstable constituents As a furthermodification, one of the above described extracts from which the heavyconstituents have not yet been removed, maybe added to the highlyrefined lubricating oil which it is desired to modify, and the mixturethereof may be treated for the purpose of removing said heavierconstituents of the extract. This may be by means of a clay treatmentaccording to any well known procedure such as that employing percent ofa filtering or bleaching clay at temperaturein the neighborhood of 350F.

' Again, a product may be obtained by adding a quantity of the originaldewaxed stock to the highly refined lubricating oil product and claytreating to remove the heavy constituents and other constituentsremovable by clay. The quantity of stock added will be that sufficientto introduce the necessary proportions ofsaid desired modifyingconstituents. This procedure may be followed where the remaining lighterconstituents, which would normally occur in an extract and are notremovable by the clay, do not possess objectionable ring-sticking orother characteristics. While these clay treating methods may sometimesbe employed, they are not preferred. The preference rests with the useof extracts from which the heavy extractibles have been --eli'minated,and particularly the above mentioned heart out or intermediate extractfractions from which the lighter extractibles also have been removed.

Where lubricating type oils have been subiected to clay treatment toremove various constituents} a fraction akinto the "heart cut can underpractical lubricating conditions.

, between about 13 and 18.

around 7 or 8% have been found highly efficient.

These added materials are in themselves good lubricants,'impart goodfilm strength and oiliness.

characteristics, are resistant to carbon and varnish formation and havea stabilizing effect in general upon the oils, especially upon those lowviscosity-gravity constant raflinates above referred to as highlyrefined or over-treated. purpose is to introduce only that portion ofthe described portions which will impart the desired characteristics.This statement applies also to those variations of the process wherefractions containing objectionable heavy and other constituents areadded and the blend clay treated to remove heavy, readily reactive andother undesired materials.

These blends havelhad their corrosive and varnish-forming orring-sticking characteristics reduced to negligible amounts. Thus, saidhi hly treated or highly parafiinic oils have been modified by'return ofnatural constituents in order to restore the non-corrosiveandnon-ring-stiching characteristics which they would have home hadtheabove mentioned protective constituents not been removed by heavyrefining. This renders such highly parafilnic oils thoroughlyserviceable Where extracts are themselves solvent extracted forseparation of intermediate from lighter constituents, such as rin-sticking materials, the same ype of selective solvent elsewherementioned may he used.

The extract fractions above mentioned as having lubricatingcharacteristics in themselves when employed for the present purposes,contain large quantities of complex organic materials including sulfurcompounds, nitrogen compounds, aromatics, unsaturates, and the like.Presumably some or all of these constituents have the desired effects.The heavy tarry and resinous constituents and unstable aromatic andunsaturated constituents as well as asphaltenes have been largelyremoved, thereby leaving only rela: tively stable materials togetherwith naphthenic constituents carried along in thetreatment. Thematerials desired have an A. P. 1". gravity range They appear to besolvents or plasticizers for gums and varnishes which tend to form' inengine operation and cause ring sticking, and to overcome or inhibitformation of corrosive constituents. This theory is presumed torepresent their function but applicants do not Wish to be bound thereto.

The addition of the fractions herein described to over-refined orheavily refined lubricating oils which tend to possess corrosive orring-sticking characteristics, produces a stabilizing effect upon suchhighly treated oils of low V. GAL. and prevents or greatly reduces suchcorrosiveness and ring sticking. Also there is ,a tendency to resistformation of carbon and'variation at high operating, temperaturesthereby especially adapting theseoils to extreme service coonditions asin the case of airplane engines and Diesel engines.

The.

These disclosures are to be taken as illustrative and not limiting ofthe generic invention, it being evident that other variations within thescope of the claims may be developed by those skilled in the art. Thus,fractions kindred to the described "heart cut," and having similarcharacteristics and performing like .functions, may be used even thoughtheir gravity be difierent, for example somewhat lighter in specificgravity.

We claim:

1. Highly refined parafilnlc type lubricating oil of low viscositygravity constant and otherwise havln'g tendencies to develop corrosiveand ring sticking characteristics, containing added minor proportions ofnon-parafilnic selective-solventextract fractions from petroleumlubricating stocks which fractions are substantially entirely stablearomatic and naphthenic materials and are free from tarry, unstable,highly reactive and highly aromatic fractions obtainable from saidfractions having lubricating properties and being free fromthe lightestextract constituents and from the heaviest extract constituentsincluding the more unstable and reactive constituents.

3. Mineral lubricating oil comprising heavily solvent-treated parafllniclubricating oil, and added minor proportions of solvent extractfractions of lubricating, 011 stock added as such, which fractions aresoluble in selective solvents 'for non-paraflinic fractions of the typerepresented by liquid sulphur dioxide, liquid sulphur dioxide-benzolmixtures, phenol and dichlorethyl ether, said fractions being free fromthe lightest constituents and also from-the heavy and more unstable andmore reactive constituents of the lubricating oil stock relatively moresoluble in said selective solvents.

. 4. An over-refined low V. G. C. highly paraffinic lubricating oilcontaining an added petroleum extract fraction added as such andobtained from a petroleum lubricating oil stock, said extract fractionbeing soluble in selective solvents for non-paraffinic materials of thepetroleum inbricating oil stock and being of relatively high molecularweight and of aromatic character relatively less soluble in saidselective solvents and free 'from heavy, tarry and highly aromatic and.reactive constituents relatively more soluble in said selectivesolvents, said extract fraction having a gravity in the order 13 to 18A. P. I. and being present in quantity sufllcient to impart to the blendfreedom from the characteristic of developing substantial corrosive andring-sticking tendencies.

5. A method for producing lubricating oils comprising treating apetroleum lubricating stock for the removal of paraffin and asphalttherefrom, treating the dewaxed, deasphalted stock with a selectivesolvent and recovering from the stock a solvent extract containingheavy, aromatic, resinous, tarry, unsaturated and naphthenicconstituents, separating said extract, removing the selective solventfrom the extract, treating the extract with a precipitantto-eliminate'heavy, highly aromatic and reactive constituents and tarryand resinous materials'and to yield a relatively stable aromatic andnaphthenic fraction, treating said fraction with a selectlve solvent forthe separation of lighter naphthenic constituents and yielding arelatively stable naphthenic and aromatic type fraction, and blendingwith a dewaxed, deasphalted, highly refined paraifinic type lubricatingoil a quantity in the order of several percent of said relatively stablearomatic-type extract fraction suflicient to impart non-corrosive andnon-ring-sticking characteristics to said rafllnate.

6. A method according to claim 5 wherein the highly parafilnic raflinateis treated with said selective solvent to possess aviscosity-gravity-constant below about 0.810, and the stable aromaticfraction to be added to said rafiinate is treated to possess aviscosity-gravity constant of about 0.8800.9l0'and a gravity above about13 A. P. I.

7. A mineral lubricating oil containing as major constituents highlyrefined solvent-treated parafilnic type mineral lubricating oilfractions and added stable non-parafflnic lubricating fractions added assuch including non-reactive aromatic and naphthenic materials soluble inselective solvents for said non-paraffinic materials, the lubricatingoil being free from reactive and unstable fractions which would berelatively more soluble in said selective solvents and beingsubstantially free from the characteristic of de- 1 veloping corrosionand ring sticking tendencies.

ULRIC B. BRAY. DONALD E. CARR.

